The present invention is concerned with a method of manufacture of breadcrumb and with a production line for breadcrumb manufacture, and particularly (but not exclusively) with a method and production line for manufacture of Japanese breadcrumb.
Breadcrumb products have numerous variations but basically fall into three categories which are currently usually all made on dedicated production plants:
i. American breadcrumb;
ii. Japanese breadcrumb; and
iii. Cracker meal or rusk.
American breadcrumb can be made on a conventional tin bread plant or by sheeting dough then proving and baking before cooling, grinding and drying the finished product. A lightly coloured golden crust is usually required, contributing colour to the crumb itself, and results from either conventional baking in an oven or toasting in the dryer.
Cracker meal or rusk is made from a high density dough which is sheeted and baked then ground, dried and milled. The dough sometimes has a coloured crust, resulting from its conventional baking, which contributes to the colour of the resulting crumb.
No crust is wanted on Japanese breadcrumb and it is currently made in the following continuous processes:
a. Bread dough pieces are moulded and several pieces are placed in a container with two sides forming electrodes. The pieces are proved then baked by passing an electric current through the dough, a process which creates heat within the dough and avoids formation of crust on its exterior. The growth of the dough pieces is constrained by the container assisting in forming the resulting grain structure in the bread in one direction. The dough pieces are cooled to set the grain structure then ground and dried.
b. The bread dough can also be mixed and structured in an extruder, a continuous mixer or batch mixer. The resulting dough is formed to give an elongated grain structure then baked using a microwave tunnel oven to give no crust. The dough pieces are cooled to set the grain structure then ground and dried.
In each case the result is a distinctive low density, needle-shaped crumb with no crust content.
In method (a) the pre forming and the constraint of the growth of the dough during baking is important in giving the resulting crumb its characteristic properties, including its shape. However the provision of containers for the dough creates its own difficulties where the method is to be implemented on an industrial scale, not least because it demands a specialised production line not suited to production of other types of crumb.
A first objective of the present invention is to provide a method and apparatus suitable for manufacture of Japanese crumb which does not utilise containers for constraint of the dough during baking. It is particularly desired that the method and apparatus should be capable of continuous throughput.
In accordance with a first aspect of the present invention there is a method of breadcrumb manufacture comprising:
preparing dough;
sheeting the dough;
disposing the sheeted dough on a conveyor and deforming the sheeted dough back and forth to form the dough into an undulating configuration;
baking the dough by conveying same through a tunnel oven; and
converting the baked dough into breadcrumb.
Where the method is used for manufacture of Japanese breadcrumb, the configuration of the dough on the baking conveyor can be such that adjacent regions of the dough which are upstanding from the conveyor contact, whereby the dough constrains itself during baking. The adjacent upstanding regions of the dough may be in contact prior to baking or may be close enough together to come into contact as the dough expands during baking. In either case the result is that the dough can expand upwardly away from the conveyor but is constrained at least to some degree against expansion in other directions, thereby maintaining the grain structure required for Japanese crumb.
The oven may be an air radio frequency assisted oven. This type of oven will be referred to herein by the letters ARFA.
The undulating configuration of the dough can also be beneficial during manufacture of other types of crumb since it allows a sheet of dough to be compactly arranged on the baking conveyor, thereby improving the volume throughput of dough which can be achieved by the oven.
The undulating configuration of the sheeted dough is straightforwardly achieved, in a particularly preferred method according to the present invention, by passing the dough from a transit conveyor onto a subsequent conveyor with the transit conveyor running at a higher speed than the subsequent conveyor.
Trials have shown that in this way a regularly formed undulating configuration can be reproducibly achieved. By adjusting sheet thickness and conveyor speed differentials in the structure and texture of the resulting baked dough can be varied.
In accordance with a second aspect of the present invention there is a line for breadcrumb production comprising:
means for preparing dough or for receiving pre-prepared dough;
means for sheeting the dough;
means for disposing the sheeted dough on a baking conveyor and deforming the sheeted dough back and forth to form the dough into an undulating configuration upstanding from the conveyor""s surface;
a tunnel oven through which the baking conveyor is arranged to convey the dough to bake same; and
means for converting the baked dough into breadcrumbs.
The modes of heating currently used for Japanese crumb manufacture also give rise to problems. Method (a) above, involving ohmic heating of the dough, does not allow in line cleaning and moisture is rapidly released from the containers during baking. This moisture condenses since the baking enclosure is not above 100xc2x0 C. and the condensed liquid combines with pieces of unbaked dough to create an unhygienic environment.
When using microwave heating as in method (b), it is important that the microwaves be adequately contained, in order to comply with regulations concerning emissions and safety. Containment of microwaves is not straightforward with continuous throughput ovens, which must have openings through which the product can enter and leave the baking chamber. In addition the penetration of microwaves into the dough is limited. The result is that while Japanese crumb can be manufactured commercially using microwave baking, the throughput of known systems is limited.
According to a particularly preferred aspect of the present invention, baking of the dough involves heating same by means of radio frequency electromagnetic radiation.
Baking by use of radio frequencies is not in itself a new technique and has previously been applied in baking. One advantage of radio frequency heating as compared with microwave heating is that radio waves attenuate less rapidly into the dough, so that more even heating can be achieved.
The use of radio frequency heating in the above described method and production line is however particularly advantageous in manufacture of Japanese breadcrumb. Containment of radio frequency radiation can be achieved in a continuous throughput oven having relatively large openings (as compared with continuous throughput microwave ovens) and because radio waves heat volumetrically they do not create a crust on the exterior of the dough. Hence this preferred aspect of the present invention allows Japanese breadcrumb to be manufactured, on a full scale production line with high throughput and without the above described disadvantages of other methods.